Among other reasons, “Trump would be cutting off an important arm of the intelligence community -- its former employees… one of the main reasons these ex-officials retain their security clearances is so that current intelligence operatives can consult with them, taking advantage of decades of institutional wisdom.”

CNN

Constitutional lawyer Joshua Matz states, “The president properly enjoys great latitude in controlling access to sensitive information, but Trump’s use of that power to retaliate against political critics poses a clear threat to First Amendment values... [This will] cast a chill far beyond the executive branch, leading some of our most savvy experts to fall silent or speak in whispers for fear of presidential retaliation.”

Washington Post

Some point out that “even if Brennan is cleared to receive highly sensitive information, nobody has to give it to him, and if someone in Trump World is doing so

“People who don’t work at intelligence agencies shouldn’t have clearances. It’s not a free speech issue. Leakers aren’t protected by the First Amendment... A healthy step in stopping intelligence leaks and blocking bureaucratic opposition to our new President will be to carefully evaluate who’s got access to America’s sensitive secrets and take corrective action.”

Power Line Blog

Counterpoint: This “is just retaliation for political criticism... If there’s probable cause to believe any of the Obama officials mentioned in the headline are leaking then arrest them, for cripes sake. If not, just accept that they’re going to say hysterical things like accusing Trump of ‘treason’ and there’s nothing that can be done about it.”